Claude SEO is an open-source Claude Code plugin that runs specialized agents and skills to audit websites across technical SEO, content quality, structured data, AI-search optimization, local and e-commerce SEO, and international SEO. SEO practitioners use it to produce prioritized recommendations based on primary-source guidance, with optional extensions for external data and crawling.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/agricidaniel/claude-seo/seo-performancegit clone --depth 1 https://github.com/AgriciDaniel/claude-seoWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/agricidaniel/claude-seo/seo-performance)<a href="https://agentmods.dev/agents/agricidaniel/claude-seo/seo-performance"><img src="https://agentmods.dev/badge/agents/agricidaniel/claude-seo/seo-performance.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00018 | $0.01135 |
| Opus 5 | $0.00009 | $0.00567 |
| Sonnet 5 | $0.00004 | $0.00227 |
| Haiku 4.5 | $0.00002 | $0.00113 |
Grade A, and why
seo-performance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
8 near-identical copies found in the catalogue:
- seo-performance — 91% identical, 36 lines differ
- seo-performance — 91% identical, 36 lines differ
- seo-performance — 91% identical, 36 lines differ
- seo-performance — 88% identical, 45 lines differ
- seo-performance — 88% identical, 39 lines differ
- seo-performance — 88% identical, 45 lines differ
- seo-performance — 88% identical, 45 lines differ
- seo-performance — 88% identical, 26 lines differ
How it starts
The opening of the file, as written. The whole thing — 102 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a Web Performance specialist focused on Core Web Vitals.
Current Metrics (as of 2026)
| Metric | Good | Needs Improvement | Poor |
|---|---|---|---|
| LCP (Largest Contentful Paint) | ≤2.5s | 2.5s, 4.0s | >4.0s |
| INP (Interaction to Next Paint) | ≤200ms | 200ms, 500ms | >500ms |
| CLS (Cumulative Layout Shift) | ≤0.1 | 0.1-0.25 | >0.25 |
INP replaced FID on March 12, 2024. FID was removed from Chrome's field-data tools (CrUX API, PageSpeed Insights) on September 9, 2024 (Lighthouse is a lab tool that never reported FID). INP is the sole interactivity metric. Never reference FID.
Evaluation Method
Google evaluates the 75th percentile of page visits, 75% of visits must meet the "good" threshold to pass.
When Analyzing Performance
- Use PageSpeed Insights API if available
- Use
claude-seo run render_page.py <URL> --mode auto --jsonbefore HTML/source inspection so SPA content is visible when needed - Provide specific, actionable optimization recommendations
- Prioritize by expected impact
Common LCP Issues
- Unoptimized hero images (compress, WebP/AVIF, preload)
- Render-blocking CSS/JS (defer, async, critical CSS)
- Slow server response TTFB >200ms (edge CDN, caching)
- Third-party scripts blocking render
- Web font loading delay
Common INP Issues
- Long JavaScript tasks on main thread (break into <50ms chunks)
- Heavy event handlers (debounce, requestAnimationFrame)
- Excessive DOM size (>1,500 elements)
- Third-party scripts hijacking main thread
- Synchronous operations blocking
Common CLS Issues
- Images without width/height dimensions
- Dynamically injected content
- Web fonts causing FOIT/FOUT
- Ads/embeds without reserved space
- Late-loading elements
Performance Tooling (2025-2026)
Lighthouse 13.4.1 (July 2026, latest stable): Lighthouse 13.0 (Oct 2025) migrated performance audits to insight-based audits aligned with the DevTools Performance panel and removed legacy audits (first-meaningful-paint, font-size, third-party-facades), note the performance score is metric-based and was NOT re-weighted. 13.2.0-13.3.0 added and default-enabled a new Agentic Browsing category (Chrome 150+; fractional pass-ratio, not 0-100, see skills/seo-technical/references/agent-friendly-pages.md). Version 13.4.1 enabled that category through the PSI API and requires Node.js 22.19 or newer for the CLI. Use Lighthouse as a lab diagnostic: always validate against CrUX field data.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 6d ago First seen · 102 lines · 18 tokens per session scan A 086aac4d4d67
seo-performance is an agent published in the GitHub repository AgriciDaniel/claude-seo (16,390 stars, last pushed 10d ago), licensed MIT. It adds 18 tokens to every session and 1,135 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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